Counterpoint: everything should be measured in SI units.
It makes no sense to count it in 1000-based SI units. You'll perpetually mis-align the data in whichever underlying storage technology you're using, and it's bad for performance and resource consumption.
Ask for disk sector alignment; we don’t have disk sectors any more, we use SSDs with blocks. And the sizes don’t need to have a neat number of kilobytes. Just the same as a litre of water doesn’t have a neat number of H2O molecules in it.